CDC: Do not wear face masks with one-way valves or vents

(CNN) — The US Centers for Disease Control and Prevention has released new guidance on wearing face coverings during the coronavirus pandemic. The CDC still encourages people to wear masks so they don’t infect others, but they should not have valves or vents that could allow the virus to escape the mask.

For months, America’s top health officials and experts have pounded home the message — we have to wear masks to combat this pandemic. Tonight — the US government says not just any mask will do. The CDC says we should not wear masks with one-way vents, or valves.

A trainer of front-line medical personnel, wearing protective gear, shows us why.

Gavin MacGregor-Skinner of the Global Biorisk Advisory Council: “Masks with valves have a one-way valve,” said Gavin MacGregor-Skinner of the Global Biorisk Advisory Council. “And this doesn’t work — because what happens, and we’ve known this for a long time, when I breathe out, that valve only opens and allows that air to escape from me, which could infect you.”

Public health experts say those top-of-the-line N-95 surgical masks should not be worn by members of the public. They should be reserved for front-line healthcare workers.

So — just what kind of mask should the rest of us be wearing?

“It should be really tightly-woven fabric,” said MacGregor-Skinner. “Bedsheets make ideal facial masks- because they can be cleaned. And the woven material is really tight. So again, anything like that works well. Anything- any material that stretches does not make a good mask because it will allow those respiratory drops to escape.”

Are there enough top-of-the-line masks for doctors and nurses on the front lines? For weeks, the Trump team has been telling us there are, saying this about personal protective equipment.

“PPE, we hear, remains very strong,” said US Vice-President Mike Pence.

But nurses, governors, and other front-line workers across the country have said they’re struggling to get enough masks and other supplies.

“The shortage is real,” said MacGregor-Skinner. “In the number of hospitals, nursing homes, long-term care facilities that I work in every day- yes, they’re struggling. They’re struggling with supply-chain issues.”

So the FDA has now loosened its requirements for companies to get emergency authorization for masks and other gear. This all comes as new studies and projections drive home the point: mask-wearing is, simply, a matter of life and death at this moment in the pandemic.

The Institute for Health Metrics and Evaluation at the University of Washington now forecasts America’s death toll from coronavirus will reach nearly 300,000 by December 1. But if 95% of people in the US wear masks, that number could drop by about 70,000 fewer deaths.

“It is unquestionable that if you deny the virus the opportunity to transmit, that slows the pandemic down,” said Harvard University Epidemiologist Prof. William Hanage. “If you deny it enough opportunities to transmit, it will go extinct. So everything that you can do to stop giving it the opportunity to infect another human being is extremely helpful. Masks are a large part of that.”

And front-line professionals are now saying, enough — enough of people refusing to wear masks, or simply not remembering, or caring enough, to take the precaution.

“That’s a very very little effort, minimal effort to minimize loss of life,” said emergency medicine physician Dr. Desmond Carson. “It’s ridiculous. It’s disrespectful. It’s inhumane. We’re human beings.”

Medical experts say there has been confusion on which masks to wear — and how to wear them. But one expert says what’s important during this pandemic is listening to medical leaders when they tell us what they’re learning about the virus.